Altera Corporation

Jay Schleicher

Andy Louie Lee

David Lewis

Jinyong Yuan

Henry Kim

David Cashman

Ketan Padalia

Jim Park

Stephanie T Tran

Guu Lin

Bruce B Pederson

Brad Vest

A programmable logic device (PLD) includes a plurality of logic array blocks (LAB's) connected by a PLD routing architecture. At least one LAB includes a logic element (LE) configurable to arithmetically combine a plurality of binary input signals in a plurality of stages. The LE comprises look-up table (LUT) logic having K inputs (a 'K-LUT'). The K-LUT is configured to input the binary input signals at respective inputs of the K-LUT logic cell and to provide, at a plurality of outputs of the K-LUT logic cell, respective binary result signals indicative of at least two of the plurality of stages of the arithmetic combination of binary input signals. An input line network includes a network of input lines, the input lines configurable to receive input signals from the PLD routing architecture that represent the binary input signals and to provide the input signals to the K-LUT. An output line network includes a network of output lines, the output lines configured to receive, from the K-LUT, output signals that represent the binary result signals and to provide the output signals to the PLD routing architecture. The described LUT's can perform arithmetic efficiently, as well as non-arithmetic functions.

Structures for LUT-based arithmetic in PLDs

Methods and apparatus for novel routing structures and methods that improve fitting of user-defined functions onto programmable logic devices. In particular, second time fitting is improved. Exemplary structures and methods include allowing product terms to be expanded using inputs from more than one neighboring macrocell by providing multiple expansion and bypassing paths. Also, product term OR shifting prevents macrocell output stages from being buried and made inaccessible, and macrocell outputs are provided on expander word lines, increasing efficiency of those lines, as well as conserving routing resources. Expansion, bypassing, OR shifting, and expander word lines may terminate at logic array block boundaries or may continue beyond these boundaries to other logic array blocks.

Flexible macrocell interconnect

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Santa Clara, CA, United States of America

Jay Schleicher